As a matter of practice in everyday use, we allow VFR-OTP guys to fly at whatever altitude they want, with the argument that they are OTP and are responsible for their own terrain avoidance. However, say the pilot of N123 is VFR-OTP is in VFR conditions and clouds close in above him and now is requesting a hard altitude. Legally since N123 is below the MEA on the airway, as well as below the minimum IFR altitude for the area, we cannot issue a hard altitude, as we cannot ensure terrain/obstruction clearance in the climb to a legal altitude.
I believe you have already answered your question in this paragraph. N123 is below the MEA/MOCA (Minimum Obstruction Clearance Altitude), therefore he cannot be given a clearance unless he climbs to the MOCA.
Since this free spirit is operating VFR below the IFR en-route airspace structure, he
IS flying VFR. You are maintaining his IFR flight plan as a professional courtesy. If he encounters a lowering cloud deck and requests a hard altitude, you may only clear him to maintain whatever altitude will be necessary for him to navigate depending on his equipment suffix. If N123 filed as a /A (VOR receivers only and no IFR GPS) he MUST maintain the MEA to ensure proper navigation reception of the ground based stations he is required to use to determine his position. If N123 filed as a /U, /G, /Q or whatever equivalent (panel mounted IFR approved GPS box with or without approach capability) then ATC can issue a clearance to maintain the MOCA, since his navigation does not require a minimum altitude to receive ground based stations.
So basically this guy is now asking you to reactivate his IFR flight plan and his IFR clearance. You as ATC cannot give him a Climb Clearance since he is beneath your airspace. All you can do for him is to clear him to MAINTAIN whatever minimum altitude is needed to be within the IFR en-route airspace structure. His climb will be at his own risk. This is the risk he assumed when he asked for an VFR-OTP clearance and then failed to maintain an appropriate IFR altitude.
My $.02
RC
